TIPS AND PITFALLS
Keep the exercise simple to begin with and try not to overdo it or complicate things too early. This exercise can be harder than it sounds. You want to keep a regular stride and even distance and be able to repeat it consistently six or seven times. Be patient and build it up slowly.
Lengthening the canter stride is usually straightforward, but some horses can struggle with maintaining the canter when slowing the movement. A good tip is to imagine that one of those fairground grabber machines has got hold of your head and is pulling you upwards — I find visualising that while asking the horse to shorten helps. Keep a bit of leg on while you do it to remind the horse to keep the canter.